added isEditorAreaVisible in PapyrusModelListener

Change-Id: I9617190723b9fbc1efb71dda4c5b5bcfce2f2d19
Signed-off-by: Alberto Debiasi <adebiasi@fbk.eu>

plugins/contracts/org.polarsys.chess.contracts.chessextension/src/org/polarsys/chess/contracts/chessextension/listeners/PapyrusModelListener.java

@@ -48,8 +48,10 @@ public class PapyrusModelListener implements IPapyrusListener {
 	@Override
 	public void notifyChanged(Notification notification) {
 		Object notifier = notification.getNotifier();
-		if(notifier instanceof Class){
+		
+		if((notifier instanceof Class)&(PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().isEditorAreaVisible())){
 			Class cblock = (Class) notifier;
+			
 			if(notification.getEventType() == StereotypeExtensionNotification.STEREOTYPE_APPLIED_TO_ELEMENT){
 				if(cblock.getAppliedStereotype(CONTRACT) != null){